The present invention relates to an applicator roll for applying a liquid composition to the individual fibers of a fan of fibers contacting the roll. More particularly, the present invention relates to an applicator roll for applying a liquid composition to the individual fibers of a fan of fibers contacting the roll, wherein the negative effects of fiber-to-roll contact are minimized.
One or more fiberglass strands used, for example, in manufacturing fiberglass-reinforced products, typically are formed by gathering the individual fibers of a fan of glass fibers exiting a glass fiber-forming bushing and by combining the individual glass fibers into one or more strands. A sizing composition is applied, such as, by an applicator roll, to the individual fibers, wherein the sizing composition serves to reduce fiber stress caused by, for example, fiber-to-fiber friction associated with direct fiber-to-fiber contact. The applicator roll typically is cylindrical, is constructed from graphite and is driven to rotate at a modest rotational velocity, as compared to the tangential linear velocity of the fibers as they pass over (and typically contact) the roll.
A sizing composition is applied to the roll, such as, for example, by submerging a portion of the roll into a shallow pool of sizing composition contained within a pan. The roll is then rotated such that the sizing composition is transferred to a position of the roll, whereat the fan of fibers momentarily contact, or Akiss@, the roll and pick up a small quantity of the sizing composition. The amount of sizing applied to the fibers by the applicator roll is controlled, for example, by controlling the rotational velocity of the roll relative to the tangential linear velocity of the fibers as they kiss the roll. U.S. Pat. No. 4,517,916 to Barch, et al. is illustrative of prior art attempts to provide a cylindrical applicator roll for applying a chemical treatment to textile fibers.
With reference to FIG. 1, the roll R typically is mounted such that the linear axis CR thereof is horizontal, and as such, a point A on the periphery of the roll R travels at a velocity vA residing exclusively within a vertical plane PA perpendicular to the axis CR of the roll R. That is, as roll R rotates about axis CR, peripheral points of the roll, being each a fixed distance from the axis CR of the roll R, travels at the same linear tangential velocity. For example, point A, located on the periphery of roll R within plane PA, travels at velocity vA, which is the same as velocity vC of point C, which also is located on the periphery of the roll R, but within plane PC, which is parallel to, but spaced from, plane PA. Moreover, all peripheral point velocities, for example, velocities vA, vB, vC, of points A, B, C, respectively, are of equal magnitude.
Fibers F1, F2, F3, which together form a fiber fan N generally converging from a wide upper end thereof near the glass-forming bushing (not shown) to a narrow lower end thereof near a radial gathering Ashoe@ roll (not shown in FIGS. 1 and 2), each contact the periphery of applicator roll R, for example, at points A, B, C, respectively, and travel at velocities v1, v2, v3, respectively, towards the gathering shoe. Velocities vA, vB, vC are much smaller than velocities v1, v2, v3, respectively.
With additional reference to FIG. 2, and in referring only to point A, fiber velocity v1 lies in a plane which is oblique to roll point velocity vA in a direction towards a centerline axis CN of fan N by an angle1. Due to point velocity vA acting on fiber velocity v1, a resultant velocity R1A acts on fiber F1, oblique to fiber velocity v1, in a direction away from fan centerline axis CN by angle1, thereby urging the fiber F1 in a direction away from fan centerline CN, and resulting in so-called Afiber walking@ of the fiber F1 towards one end R1, R2 of the roll R. of course, fiber F1, which is located between a first end R1 of roll R and fan centerline CN, will walk towards the first end R1 of roll R, whereas fiber F3, which is located between a second end R2 of roll R and fan centerline CN, will walk towards the second end R2 of roll R. Fiber walking increases fiber-to-fiber abrasion, imparts additional tensile and shear stresses within the fibers, and produces uneven coating of the sizing composition onto the fibers. Thus, it is desirable to provide a roll for applying a liquid composition to the individual fibers of a fan of fibers passing over the roll, wherein fiber walking is minimized.
Moreover, assuming that point B lies in a plane containing fan centerline CN, fiber velocity v2 is coaxial with point velocity vB, and a resultant velocity (not shown) between fiber velocity v2 and point velocity vB lies in the plane containing point centerline vB,fiber velocity v2, and fan centerline CN. Fiber F2, unlike fibers F1 and F3, then, is not urged away from fan centerline CN and does not walk towards either end R1, R2 of roll R. Rather, less tensile stress is induced in fiber F2 than is induced in fibers F1, or F3 Accordingly, fibers F1, F2, F3 of fan N experience varying degrees of tensile stress and walking, depending on the distance of the fibers F1,F2, F3 from the fan centerline CN. That is, the farther a fiber is from fan centerline, the greater the degree of tensile stress induced therein, and the greater the degree of walking experienced thereby. It is therefore desirable to provide a roll for applying a liquid composition to the individual fibers of a fan of fibers passing over the roll, wherein the negative effects of fiber-to-roll contact are minimized.
Curved rolls are known in the art for specific applications. For example, U.S. Pat. No. 3,500,524 to Jaminas and U.S. Pat. No. 4,805,274 to Gallant, et al. each teaches a roll having an adjustable radial deflection or curvature. However, neither Jaminas  greater than 524 nor Gallant  greater than 274 teaches an applicator roll for applying a liquid composition to the individual fibers of a fan of fibers passing over the roll, wherein the negative effects of fiber-to-roll contact are minimized.
The present invention is for an applicator roll used to apply a sizing composition to the individual fibers of a fan of fibers being gathered, for example, into a strand for use in fiberglass-reinforced products. The applicator roll is generally of an arcuate shape and includes a curved shaft and an elastic sleeve covering at least a portion of the shaft. The shaft includes a central axis having a curved center portion defining a radius and linear end portions extending from either end of the curved center portion. The sleeve, which is elastic and resembles a piece of rubber hose, fits over all of shaft curved center portion and over at least a portion of shaft linear end portions, then, includes a center axis which is coincident with the shaft center axis. The applicator roll is part of a sizing delivery system and is positioned adjacent to a sizing delivery assembly and upstream from a gathering shoe.
The sleeve is connected at one end thereof to a drive, which rotates the sleeve around the shaft. The sleeve is positioned relative to a sizing delivery assembly such that an outer surface of the sleeve receives liquid sizing dispensed through a slotted orifice provided in the sizing delivery assembly. Rotation of the sleeve, then, carries the liquid sizing to a location where the individual fibers of the fan of fibers kiss the outer surface of the sleeve and pick up a small quantity of the sizing composition thereby. Excess sizing is collected in a reservoir positioned beneath the roll and is re-circulated back into the sizing delivery assembly.
Because the roll is arcuate, fibers kissing the outer surface of the sleeve are each traveling in a direction which is substantially coaxial with the direction of travel of the sleeve at the point at which the fiber kisses the sleeve. Accordingly, fiber walking is substantially reduced or eliminated. Moreover, fibers are subjected to a substantially constant tensile stress, regardless of the position of the fiber relative to the fan centerline.
According to one aspect of the present invention, a roll for applying a sizing composition to a fan of one or more fibers is provided, comprising a shaft having a curved central axis, and a sleeve covering at least a portion of the shaft, the sleeve being rotatable relative to the shaft, wherein each fiber of the fan of one or more fibers contacts the sleeve at an axial location along the sleeve, and wherein each fiber of the fan of one or more fibers lies substantially in a plane perpendicular to the curved central axis of the shaft at the axial location.
According to another aspect of the present invention, a method of applying a sizing composition to a fan of one or more fibers is provided, comprising the steps of providing an element having a curved central axis, rotating the element about the curved central axis, applying a coating of sizing composition to the element as the element rotates about the curved central axis, and conveying each fiber of the fan of one or more fibers over the element, whereby each fiber of the fan of one or more fibers contacts the element at an axial location along the element and moves over the element in a direction which lies substantially in a plane perpendicular to the central axis of the element at the axial location of the element, and whereby the sizing composition is transferred from the element to each fiber of the fan of one or more fibers.
According to yet another aspect of the present invention, a system for applying a sizing composition to a fan of one or more fibers is provided, comprising an element having a curved central axis, wherein each fiber of the fan of one or more fibers contacts the element at an axial location along the element and moves over the element in a direction which lies substantially in a plane perpendicular to the central axis of the element at the axial location of the element, and a sizing delivery assembly for providing sizing composition to a surface of the roll, the sizing composition being transferred to each of the fibers of the fan of one or more fibers when the fibers contact the element.
It is an object of the present invention to provide a roll for applying a liquid composition to the individual fibers of a fan of fibers passing over the roll, wherein fiber walking is minimized.
It is another object of the present invention to provide a roll for applying a liquid composition to the individual fibers of a fan of fibers passing over the roll, wherein the negative effects of fiber-to-roll contact are minimized.
These and additional objects, features and advantages of the present invention will become apparent to those reasonably skilled in the art from the description which follows, and may be realized by means of the instrumentalities and combinations particularly pointed out in the claims appended hereto.